140 PERMIAN FOSSILS. 
Cleiothyris pectinifera, as British, is only known to occur in the shell-limestone of 
Humbleton Quarry, where it is not common; and in the Breccia of Tynemouth Cliff, 
where it is extremely scarce: the testiferous specimen represented in Pl. X, figs. 1, 
2, 3, 4, is the only one I have procured in the latter place. It is also a scarce 
fossil in Germany; since Dr. Geinitz records its occurrence in only two localities, 
Milbitz and Corbusen in the under Zechstein. The Russian shells included in the 
synonymy from de Verneuil, were found in the Permian marls of Kirilof, Tioplova 
west of Arzamas, and Nikefur in Bielebei, Orenbourg. Count Keyserling records its 
occurrence in Permian limestone on the Wol near Kischerma, and on the Wym near 
Seregof, in Petschora-Land. 
Sus-ctass ANCYLOPODA, J. E. Gray. 
Diagnosis.-—“‘ The oral arms recurved.” 
This division is distinguished from its co-ordinate, Melictopoda, in having the labial 
appendages or oral arms recurvedly folded, and not spirally twisted as in the latter,— 
a difference which is in like manner participated by the apophyses of these organs. 
It will be recollected that certain groups of [elictopoda have their labial appendages 
either entirely unsupported, or only slightly sustamed by an apophysary system; for 
example, Sarcicobrachia and Hypothyride ;—probably the same may be predicated of 
the Ancylopodous groups Rhynchoride and Argiopide. 
Mr. Gray has divided the present sub-class into two orders, Ancylobrachia and 
Cryptobrachia ; but for the reasons elsewhere given (vide ante, pp. 81-2.), it has been 
deemed advisable to merge both into one, distinguishing it by the first appellation. 
Order ANCYLOBRACHIA, Gray. 
Diagnosis. —“ The oral arms” in general ‘‘ affixed to calcareous plates, forming hoops 
attached to the hinge-margin of the ventral valve (dorsal, 062s), and prominent in its 
999 
cavity.” 
Having placed in the present order the families 4rgiopide and Rhynchoride, the 
1 Mr. Gray adds: ‘‘and affixed to fixed appendages on the disc of the ventral valve. Shell minutely 
and closely perforated.” (Vide Annals and Mag. of Nat. Hist., 2d series, vol. ii, p.435.) In the next page 
the following diagnosis is added: “The oral arms not extensile, or only at the tip; on fixed shelly supports, 
or in grooves in the under or ventral valve; the mantle is adherent to the shell, the substance of the shell 
being pierced with numerous minute perforations, which are pervaded by the processes of the mantle.” I 
have considered it best to leave out the foregoing in the text, as some Anchylopods appear to be without 
shelly supports: as to the shell being perforated, this appears to be a character general in the Pallio- 
branchs. 
2 Annals and Magazine of Natural History, 2d series, vol. 1, p. 435. 
